This invention is generally directed to developer compositions, and more specifically, the present invention relates to developer compositions with coated carrier components, or coated carrier particles that can be prepared by, for example, dry powder processes. More specifically, the present invention relates to carrier compositions comprised of a core and thereover copolymers of styrene and a monoalkylaminoalkyl methacrylate, or styrene and a dialkylaminoalkyl methacrylate.
More specifically, the present invention relates to carrier particles comprised of a core with a coating thereover of copolymers of styrene and diisopropylaminoethyl methacrylate, styrene copolymers with monoalkyl or dialkyl aminoethyl methacrylate, t-butylaminoethyl methacrylate, and the like. The carrier may include the copolymer coating thereover in admixture with other suitable polymers, and more specifically, with a second polymer, such as a fluoropolymer, polymethylmethacrylate, poly(urethane), especially a crosslinked polyurethane, such as a poly(urethane)polyester and the like, and moreover the copolymer, or mixture of polymer coatings may contain a conductive component, such as carbon black, and which conductive component is preferably dispersed in the copolymer coating. With the conductive component, there are enabled carriers with increased developer triboelectric response, that is, stable triboelectric values up to about 80 microcoulombs per gram at relative humidities of from about 20 to about 90 percent, improved image quality performance, excellent high conductivity ranges of, for example, from about 10.sup.-10 to about 10.sup.-7 (ohm-cm).sup.-1, and the like. The carrier triboelectrical charge may be, for example, a carrier tribo range of from about a plus (positive charge) 25 to about 80, and preferably from about a positive 35 to about a positive 70 microcoulombs per gram as determined by the known Faraday Cage method.
The carrier particles of the present invention can be selected for a number of different xerographic copiers and printers, such as high speed color xerographic copies, in the range of, for example, about 70 to about 135 impressions per minute, printers, digital copiers, and more specifically, wherein colored copies with excellent and substantially no background deposits are achievable in copiers, printers, digital copiers, and the combination of xerographic copiers and digital systems. Developer compositions comprised of the carrier particles illustrated herein and prepared, for example, by a dry coating process are generally useful in electrostatographic or electrophotographic imaging systems, especially xerographic imaging and printing processes, and digital processes. Additionally, the invention developer compositions comprised of substantially conductive carrier particles are useful in imaging methods wherein relatively constant conductivity parameters are desired. Furthermore, in the aforementioned imaging processes the triboelectric charge on the carrier particles can be preselected depending on the polymer composition and dispersant component applied to the carrier core and the type and amount of the conductive component selected.